Modern computers require media in which digital data can be quickly stored and retrieved. Magnetizable (hard) layers on discs have proven to be a reliable media for fast and accurate data storage and retrieval. Disc drives that read data from and write data to hard discs have thus become popular components of computer systems. To access memory locations on a disc, a read/write head (also referred to as a “slider”) is positioned slightly above the surface of the disc while the disc rotates beneath the read/write head at an essentially constant velocity. By moving the read/write head radially over the rotating disc, all memory locations on the disc can be accessed. The read/write head is typically referred to as “flying” head because it includes a slider aerodynamically configured to hover above the surface on an air bearing located between the disc and the slider that is formed as the disc rotates at high speeds. The air bearing supports the read/write head above the disc surface at a height referred to as the “flying height.”
In conventional disc drives, one or more hard discs are coupled to and rotate about a spindle, each disc presenting two opposite substantially flat surfaces for reading and recording. Typically, multiple rotating hard discs are stacked in a parallel relationship with minimal spacing between adjacent discs. Accordingly, the read/write heads must be designed to move within the narrow space between adjacent discs and fly close to the disc surfaces. To achieve this positional capability, the read/write heads in typical disc drives are coupled to the distal end of thin, arm-like structures called head gimbal assemblies, or HGAs. The HGAs are inserted within the narrow space between adjacent discs. The HGAs are made of materials and thicknesses as to be somewhat flexible and allow a measure of vertical positioning as the read/write heads hover over the surface of the rotating discs.
Each HGA is coupled at its proximal end to a rigid actuator arm. The actuator arm horizontally positions the HGA and read/write head over the disc surface. In conventional disc drives, actuator arms are stacked, forming a multi-arm head stack assembly. The head stack assembly moves as a unit under the influence of a voice coil motor to simultaneously position all head gimbal assemblies and corresponding read/write heads over the disc surfaces.
The HGA in a typical disc drive includes four components: 1) a magnetic recording (MR) head or slider, features a self-acting hydrodynamic air bearing and an electromagnetic transducer for reading and writing data on a spinning magnetic disc; 2) a gimbal, which is attached to the slider, is compliant in the slider's pitch and roll axes for the slider to follow the topography of the disc, and is rigid in yaw and in-plane axes for maintaining precise slider positioning; 3) a load beam or flexure, which is attached to the gimbal and to the actuator arm which attaches the entire HGA to the actuator. The load beam is compliant in a vertical axis to allow the slider to follow the topography of a disc, and is rigid in the in-plane axes for precise slider positioning. The load beam also supplies a downward force that counteracts the hydrodynamic lifting force developed by the slider's air bearing; and 4) a head interconnect circuit, which is disposed on the load beam and electrically coupled to the transducer of the slider. The head interconnect circuit sends the electric signals to and from the transducer of the slider/MR head. In one embodiment, the gimbal is assembled separately from the head interconnect circuit. In another embodiment, the gimbal is assembled together with the head interconnect circuit.
As the volume of HGAs in a disc drive increases from year to year, and the size of the components of the HGAs continue to shrink, the amount of labor and cost in manufacturing the HGAs becomes a large percentage of the total manufacturing cost. To decrease labor and cost, many disc drive manufacturers have implemented automation in an HGA assembling process. Circuitized or “wireless” designs for a head interconnect circuit of an HGA have been used to replace an individual or twisted pair wire designs for a head interconnect circuit. Further, to connect electrical bond pads of a slider/MR head to electrical bond pads of a head interconnect circuit in an automatic HGA line, several manufacturers have used a corner ball bonding technique between the bond pads of the slider/MR head and the bond pads of the head interconnect circuit. FIG. 2 illustrates a typical corner ball bonding assembly for electrically connecting a slider/MR head to a head interconnect circuit. Such bonding process often uses an ultrasonic bonding.
The problem associated with a corner ball bonding assembly is that it requires a three-dimensional interconnection between the bond pads of a slider/MR head and the bond pads of a head interconnect circuit. The three-dimensional interconnection requires that the slider/MR head, a conductive ball, and the head interconnect circuit be available at the same time in such a small three-dimension while the slider/MR head is being bonded to the head interconnect circuit. The three-dimensional interconnection corner ball bonding technique drives expensive tooling and rigid fixturing of the slider/MR head. Accordingly, the cost of manufacturing an HGA is still very high.
It is with respect to these and other considerations that the present invention has been made.